Determination of oleanolic acid and ursolic acid in Chinese medicinal plants using HPLC with PAH polymeric C18

Background: The RP-HPLC resolution of two triterpenic acid isomers was unstable. Objective: To separate the oleanolic acid (OA) and ursolic acid (UA) simply within RP-HPLC. Materials and Methods: The separation ability of five stationary phases was studied with the retention effect of their carbon loads. Also the resolution effects of mobile phase composition and different column temperatures were systematically investigated by using Drylab® (Rheodyne LLC.) after evaluating chromatograms automatically. Results: The best available resolution of two bioactive isomers was achieved (r = 3.4) via using PAH (polycyclic aromatic hydrocarbons) polymeric C18 bonded phase column. The chromatographic system was applied to the quantification in ten Chinese medicinal plants and the validation was carried out and the precision (RSD ≤1.34%), the linearity (r ≥0.9998) and the recovery (range from 92.1% to 102.6%) were acceptable. Conclusion: It is clear that the method was simple, rapid and reliable for the quantification of two compounds in new HPLC method within PAH polymeric C18.